Enhanced Particle Removal in Fluorinated Liquids—An Application in Nuclear Decontamination

An experimental cleaning system has been developed to demonstrate the decontamination of model electronic circuit boards by this cleaning process. The media used in this process are a wash solution of a high molecular weight fluorocarbon surfactant in a perfluorinated carrier liquid which results in enhanced particle removal, followed by a perfluorinated carrier liquid rinse. The perfluorinated liquids of interest, which are recycled in the process, are inert, nonflammable, generally safe to use, and do not present a hazard to the atmospheric ozone layer. The cleaning experiments were performed at the MIT Nuclear Reactor Laboratory. The radioactive particles removed from the circuit boards were captured by 0.22 μm filters with a filtration efficiency of 99.5% per stage. Compatibility tests were performed on these model electronic circuit boards. The results obtained show that neither the process fluids used nor the maximum level of the ultrasonic agitation applied harmed the circuit boards or the circuit components. All the circuit boards used in these tests were still functional after the cleaning experiments. A three log reduction in contamination was obtained in 1 hour. These data indicate that this process, once implemented on a large scale, will offer users in the nuclear industry a practical and cost effective means of decontaminating and recovering a wide variety of tools and instruments.     

Phenocopies for deafness and goiter development in a large inbred Brazilian kindred with Pendred's syndrome associated with a novel mutation in the PDS gene

Pendred's syndrome is an autosomal recessive disease characterized by goiter, impaired iodide organification, and congenital sensorineural deafness. The gene mutated in Pendred's syndrome, PDS (Pendred's syndrome gene), was cloned very recently and encodes the putative sulfate transporter pendrin. Pendred's syndrome may account for up to 10% of the cases with hereditary hearing loss, and pendrin mutations have also been found in a kindred with non-syndromic deafness. In this study, 41 individuals from a large, highly inbred pedigree from Northeastern Brazil were examined for features of Pendred's syndrome. Linkage studies and sequence analysis of the coding region of the PDS gene were performed with DNA from 36 individuals. The index patient, with the classical triad of deafness, positive perchlorate test, and goiter, was found to be homozygous for a deletion of thymidine 279 in exon 3, resulting in a frameshift and a premature stop codon at amino acid 96. This alteration resulted in truncation of the protein in the first transmembrane domain. Two other patients with deafness were found to be homozygous for this mutation; 19 were heterozygous and 14 were homozygous for the wild type allele. Surprisingly, 6 deaf individuals in this kindred were not homozygous for the PDS gene mutation; 3 were heterozygous and 3 were homozygous for the wild type allele, suggesting a probable distinct genetic cause for their deafness. All 3 homozygous individuals for the PDS mutation had goiters. However, goiters were also found in 10 heterozygous individuals and in 6 individuals without the PDS mutation and are most likely caused by iodine deficiency. In conclusion, we identified a novel mutation in the PDS gene causing Pendred's syndrome. The comparison of phenotype and genotype reveals, however, that phenocopies generated by distinct environmental and/or genetic causes are present in this kindred and that the diagnosis of Pendred's syndrome may be difficult without molecular analysis.     

Rißbildung in turmartigen Tragwerken: Schleuderbetonmast versus Stahlbetonschornstein

Crack Formation in Tower like Structures: Mast of centrifugal concrete vs. chimney of normal concrete Numerous tower like structures are used as antenna carriers in the age of cell phones. Most of them are for this aim designed masts of high strength concrete and old purposely equipped chimneys. Some of those structures show conspicuous vertical cracks which may affect the wind bearing capacity and thus, have to be assessed. In connection with this task the fact must be considered that the experiences with crack behavior of normal concrete structures are only conditionally valid for masts of centrifugal concrete. Regarding all this the differences in crack behavior of high strength masts and low strength chimneys are addressed in this paper. The investigation results were gained by the computation method from DIN V 1056, DIN EN 13084 and CICIND Model Code and represent an important part of the quality assurance of the tower like structures.